Seafood physical characteristic estimation system and method

ABSTRACT

Systems and methods for estimating a physical characteristic of a seafood product are provided. In one system, the estimate is based on a slope defined by a ratio of changes in peak resonant amplitude and frequency of an electromagnetic resonant circuit in loaded and unloaded states. In another system, a first probe of a plurality of probes is driven with a test signal when the plurality of probes is loaded by a seafood product and the estimate is based on received test signals at one or more of the other probes. In another system, the estimate is based on the loading effect of a seafood product on an electromagnetic resonant circuit, which is also used to read an ID from an RFID associated with the seafood product. The systems and methods may be used for individual specimens, or to determine an average estimate for multiple specimens at one time.

CROSS REFERENCE TO RELATED APPLICATIONS

The present patent application claims the benefit of U.S. ProvisionalPatent Application Ser. No. 60/988,905 filed on Nov. 19, 2007, theentire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention pertains to the field of non-invasive electromagneticsensing, and more particularly to sensing for estimation of one or morephysical characteristics of seafood products.

BACKGROUND OF THE INVENTION

It is known that many aquatic invertebrates such as crustaceans gothrough a cycle of molting, in which an old hard shell is shed and a newlarger soft shell is grown. Depending on the stage of the moltingprocess, the crustacean's internal body, i.e., the “meat” portion of thelobster, may occupy a reduced part of the internal volume of the newshell as the internal body grows to occupy the new, larger shell. Theinternal structure of the crustacean, including its organs, meat andmuscle, is undersized in proportion to its new shell after molting. Inorder to “fill out” this new, oversized shell, the crustacean takes onand retains water within its internal structure. As a result, inter-moltcrustaceans (hard shell) generally produce high meat yields, whilepost-molt (soft shell) crustaceans generally produce very low meatyields.

Seafood is often an expensive food product for which a consumer pays apremium. In return, the consumer expects to receive a high qualityproduct that reflects the price paid. For example, consumers will oftenpay a premium for larger crustaceans, in terms of weight and/or size,and the consumer will generally expect the size of the crustacean tocorrespond to the amount of meat yielded by the crustacean. However, dueto the variance in the ratio of intracellular water to extracellularwater in the shell cavity of the crustacean, i.e., the ratio of theamount of water stored in the muscle or “meat” of the crustacean to theamount of water stored outside of the muscle to “fill out” the shell, alarger post-molt crustacean may not yield any more meat than a smallerpre-molt or inter-molt crustacean.

Inter-molt crustaceans can often be identified by their hard shells andother external characteristics such as color. However, these measuresare unreliable as a means to determine meat yields and are difficult toimplement as non-invasive measures on a production line. Other attemptsat sensing systems employing ultrasound or x-ray scanning systems haveproven difficult to implement and failed to accurately distinguishbetween different shell hardnesses and/or different meat yields.

Beyond meatedness, the molt state of a crustacean can also be used as a“health” indicator that provides a seafood processor with the advantageof being able to assess anticipated mortality rates during storage.

Conventional meat yield sensing systems have relied on an assumedcorrelation between the refractive index (RI) of the blood ofcrustaceans and the stage of molt of a crustacean, and hence themeatedness of the lobster. However, while these methods may be fairlyaccurate at predicting meat yield, they require an invasive blood testof the crustacean and the use of a refractometer to determine the RI ofthe blood, which is impractical in a production plant setting at typicalproduction rates.

In addition, conventional means of detecting meatedness are difficult toassess on live seafood product, at production speeds, because of varyingpose/position of the crustacean under test.

SUMMARY OF THE INVENTION

The ability to identify, for example, lobsters with a high meat yieldmay allow seafood distributors or retailers to provide their customerswith a greater level of confidence that a given lobster will have atleast a minimum meat yield, and may also allow for a further sorting oflobsters into quality grades that are appropriate for differentcustomers.

According to one aspect of the present invention, there is provided amethod comprising: determining a minimum peak resonant frequencyF_(resonant) _(—) _(min) and peak resonant amplitude A_(resonant) _(—)_(min) at F_(resonant) _(—) _(min) of an electromagnetic resonantcircuit when loaded by a seafood product; and estimating a physicalcharacteristic of the seafood product based on a slope defined by:

(A_(resonant) _(—) _(ref)−A_(resonant) _(—) _(min))/(F_(resonant) _(—)_(ref)−F_(resonant) _(—) _(min)),

where F_(resonant) _(—) _(ref) is a reference peak resonant frequency ofthe electromagnetic resonant circuit in an unloaded state, andA_(resonant) _(—) _(ref) is a reference peak resonant amplitude of theelectromagnetic resonant circuit in the unloaded state.

In some embodiments, the method further comprises: determining thereference peak resonant frequency F_(resonant) _(—) _(ref) and thereference peak resonant amplitude A_(resonant) _(—) _(ref) of theelectromagnetic resonant circuit in the unloaded state.

In some embodiments, the method further comprises: determining a weightof the seafood product, wherein estimating the physical characteristiccomprises estimating the physical characteristic based on the slope andthe weight of the seafood product.

In some embodiments, determining F_(resonant) _(—) _(ref) andA_(resonant) _(—) _(ref) comprises: applying a plurality of excitationfrequencies to the electromagnetic resonant circuit in the unloadedstate; measuring an amplitude of an output of the electromagneticresonant circuit for each one of the excitation frequencies; determiningA_(resonant) _(—) _(ref) as a peak amplitude of the measured amplitudes;and determining F_(resonant) _(—) _(ref) as the excitation frequencycorresponding to the peak amplitude of the measured amplitudes.

In some embodiments, determining F_(resonant) _(—) _(ref) andA_(resonant) _(—) _(ref) comprises: maintaining a record of peakresonant amplitudes and frequencies in previous unloaded states;applying a plurality of excitation frequencies to the electromagneticresonant circuit in the current unloaded state; measuring an amplitudeof an output of the electromagnetic resonant circuit for each one of theexcitation frequencies; determining A_(resonant) _(—) _(ref) as arolling average of a number of the peak resonant amplitudes of theprevious unloaded states and the peak amplitude of the current measuredamplitudes; and determining F_(resonant) _(—) _(ref) as a rollingaverage of a number of the peak resonant frequencies of the previousunloaded states and the peak resonant frequency of the current measuredamplitudes corresponding to the peak amplitude of the current measuredamplitudes.

In some embodiments, the method further comprises: maintaining adatabase of A_(resonant) _(—) _(ref), A_(resonant) _(—) _(min),F_(resonant) _(—) _(ref) and F_(resonant) _(—) _(min) for each seafoodproduct.

In some embodiments, the method further comprises: maintaining theestimated physical characteristic for each seafood product in thedatabase.

In some embodiments, the method further comprises: performing linearregression on the slope to determine a linear relationship between theslope and the physical characteristic.

In some embodiments, the method further comprises: updating a webpagebased on contents of the database.

In some embodiments, the method further comprises: determining athreshold as a boundary between quality grades; and determining aquality grade of the seafood product by comparing the slope to thethreshold.

In some embodiments, determining the threshold comprises performing adata mining algorithm.

In some embodiments, the method further comprises: calibrating by:determining a slope for a calibration seafood product with a knownphysical characteristic; and adjusting a function for estimating thephysical characteristic based on any discrepancy between the knownphysical characteristic and the physical characteristic estimate basedon the determined slope.

In some embodiments, the seafood product comprises a plurality ofspecimens.

In some embodiments, the plurality of specimens are contained in acrate.

In some embodiments, the method further comprises: reading an ID from aRadio Frequency Identification (RFID) tag associated with the seafoodproduct with the electromagnetic resonant circuit; and associating theID of the RFID tag associated with the seafood product with informationrelating to the estimation of the physical characteristic of the seafoodproduct.

In some embodiments, associating the ID of the RFID tag associated withthe seafood product with information relating to the estimation of thephysical characteristic of the seafood product comprises at least oneof: transmitting, via the electromagnetic resonant circuit, informationrelating to the estimation of the physical characteristic of the seafoodproduct to the RFID tag associated with the seafood product for storageon the RFID tag; and storing the information relating to the estimationof the physical characteristic of the seafood product in a database,such that the information is associated with the ID of the RFID tag.

In some embodiments, the method further comprises: reading the RFID tagassociated with the seafood product to retrieve the information relatingto the estimation of the physical characteristic of the seafood productassociated with the RFID tag; and sorting the seafood product into oneof at least two grades based on the information retrieved from the RFIDtag.

According to another aspect of the present invention, there is provideda system comprising: a sensor comprising an electromagnetic resonantcircuit; a controller, functionally connected to the electromagneticresonant circuit, that: determines a minimum peak resonant frequencyF_(resonant) _(—) _(min) and peak resonant amplitude A_(resonant) _(—)_(min) at F_(resonant) _(—) _(min) of the electromagnetic resonantcircuit when the electromagnetic resonant circuit is loaded by a seafoodproduct; and estimates a physical characteristic of the seafood productbased on a slope defined by:

(A_(resonant) _(—) _(ref)−A_(resonant) _(—) _(min))/(F_(resonant) _(—)_(ref)−F_(resonant) _(—) _(min))

where F_(resonant) _(—) _(ref) is a reference peak resonant frequency ofthe electromagnetic resonant circuit in an unloaded state, andA_(resonant) _(—) _(ref) is a reference peak resonant amplitude of theelectromagnetic resonant circuit in the unloaded state.

In some embodiments, the controller also determines the reference peakresonant frequency F_(resonant) _(—) _(ref) and the reference peakresonant amplitude A_(resonant) _(—) _(ref) of the electromagneticresonant circuit in the unloaded state.

In some embodiments, the system further comprises: a weight scale,functionally connected to the controller, that determines a weight ofthe seafood product, wherein the controller estimates the physicalcharacteristic based on the slope and the weight of the seafood product.

In some embodiments, the controller comprises a variable frequencysource, and wherein the controller determines F_(resonant) _(—) _(ref)and A_(resonant) _(—) _(ref) by: controlling the variable frequencysource to apply a plurality of excitation frequencies to theelectromagnetic resonant circuit in the unloaded state; measuring anamplitude of an output of the electromagnetic resonant circuit for eachone of the excitation frequencies; determining A_(resonant) _(—) _(ref)as a peak amplitude of the measured amplitudes; and determiningF_(resonant) _(—) _(ref) as the excitation frequency corresponding tothe peak amplitude of the measured amplitudes.

In some embodiments, the controller: maintains a record of peak resonantamplitudes and frequencies in previous unloaded states; determinesA_(resonant) _(—) _(ref) as a rolling average of a number of the peakresonant amplitudes of the previous unloaded states and the peakamplitude of the current measured amplitudes; and determinesF_(resonant) _(—) _(ref) as a rolling average of a number of the peakresonant frequencies of the previous unloaded states and the peakresonant frequency of the current measured amplitudes corresponding tothe peak amplitude of the current measured amplitudes.

In some embodiments, the system further comprises: a server having adatabase in communication with the controller, wherein the controllerstores a record in the database of the estimated physicalcharacteristic, A_(resonant) _(—) _(ref), A_(resonant) _(—) _(min),F_(resonant) _(—) _(ref) and F_(resonant) _(—) _(min) for each seafoodproduct.

In some embodiments, the server further comprises: an interfacecomprising a webpage that is updated based on contents of the database.

In some embodiments, the electromagnetic resonant circuit comprises: twosubstantially co-planar plates separated by a gap; an inductor having afirst end and a second end respectively functionally connected to thetwo substantially co-planar plates; a tickler coil inductively coupledto the inductor; and a sense coil inductively coupled to the inductor,wherein the controller applies a plurality of excitation frequencies tothe tickler coil and determines F_(resonant) _(—) _(min) andA_(resonant) _(—) _(min) based on an output of the sense coil when theelectromagnetic resonant circuit is loaded by the seafood product.

In some embodiments, the system further comprises: a biologist stationconsole functionally connected to the controller, the biologist stationconsole allowing a user to enter a known physical characteristic of acalibration seafood product, wherein the controller: determines a slopefor the calibration seafood product with the known physicalcharacteristic; and adjusts a function for estimating the physicalcharacteristic based on any discrepancy between the known physicalcharacteristic and the physical characteristic estimate based on thedetermined slope.

In some embodiments, the electromagnetic resonant circuit comprisesthree or more substantially planar plates separated by gaps.

In some embodiments, the three or more substantially planar platesdefine a volume.

In some embodiments, the seafood product comprises a plurality ofspecimens.

In some embodiments, the electromagnetic resonant circuit is part of aRadio Frequency Identification (RFID) reader.

In some embodiments, the controller is configured to perform at leastone of the following steps: transmit, via the electromagnetic resonantcircuit, information relating to the estimation of the physicalcharacteristic of the seafood product to an RFID tag associated with theseafood product; and store the information relating to the estimation ofthe physical characteristic of the seafood product in a database, suchthat in the database the information is associated with an ID of theRFID tag associated with the seafood product.

In some embodiments, the system further comprises: a second RFID readercomprising a second electromagnetic resonant circuit configured to readthe RFID tag associated with the seafood product to retrieve theinformation relating to the estimation of the physical characteristic ofthe seafood product; and a grader, functionally connected to the RFIDreader, configured to sort the seafood product into one of at least twogrades based on the information retrieved from the RFID tag.

In some embodiments, the information relating to the estimation of thephysical characteristic of the seafood product comprises a grade of theseafood product, and wherein sorting the seafood product comprisessorting the seafood product based on the grade of the seafood productstored on the RFID tag.

According to yet another aspect of the present invention, there isprovided a method comprising: driving a first probe of a plurality ofprobes with a test signal, when the plurality of probes is loaded by aseafood product; measuring received test signals at one or more otherprobes of the plurality of probes; and estimating a physicalcharacteristic of the seafood product based on the received testsignals.

In some embodiments, driving comprises sequentially driving each of theprobes of the plurality of probes with the test signal.

In some embodiments, measuring comprises measuring the received signalswith each of the other probes of the plurality of probes.

In some embodiments, the method further comprises: determiningcalibration references by: driving the first probe of the plurality ofprobes with a test signal, when the plurality of probes is unloaded; andmeasuring received test signals at the one or more other probes of theplurality of probes, wherein estimating comprises estimating based onthe calibration references and the test signals received when theplurality of probes is loaded by the seafood product.

In some embodiments, estimating comprises estimating the physicalcharacteristic as a function of a difference in magnitude between thereceived test signals and the calibration references.

In some embodiments, driving comprises driving the first probe with aplurality of test signals, each test signal corresponding to one of aplurality of frequencies.

In some embodiments, the seafood product comprises a plurality ofspecimens, and wherein estimating a physical characteristic of theseafood product comprises estimating an average physical characteristicof the plurality of specimens.

In some embodiments, the method further comprises sorting the seafoodproduct into one of at least two grades based on the estimated physicalcharacteristic.

In some embodiments, the method further comprises contacting theplurality of probes to the seafood product.

In some embodiments, the seafood product comprises a lobster, andcontacting the plurality of probes to the seafood product comprisescontacting the plurality of probes to an underside of a tail of thelobster.

In some embodiments, measuring received test signals at one or moreother probes of the plurality of probes comprises: measuring relativeimpedance of tissue occupying space between the first probe and the oneor more other probes of the plurality of probes; and generating aprofile of tissue impedance along the plurality of probes, whereinestimating a physical characteristic of the seafood product based on thereceived test signals comprises estimating the physical characteristicbased on a gradient of the profile.

According to still another aspect of the present invention, there isprovided a system comprising: a sensor comprising a plurality of probes;a controller, functionally connected to the sensor, that: drives a firstprobe of the plurality of probes with a test signal, when the pluralityof probes is loaded by a seafood product; measures received test signalsat one or more other probes of the plurality of probes; and estimates aphysical characteristic of the seafood product based on the receivedtest signals.

In some embodiments, the plurality of probes comprises a plurality ofplates defining a volume, and wherein the controller drives a firstplate of the plurality of plates with the test signal when the pluralityof plates is loaded by the seafood product within the volume.

In some embodiments, the seafood product comprises a plurality ofspecimens.

In some embodiments, the plurality of specimens are contained in acrate.

In some embodiments, the controller determines calibration referencesby: driving the first probe of the plurality of probes with a testsignal, when the plurality of probes is unloaded; and measuring receivedtest signals at the one or more other probes of the plurality of probes,wherein estimating comprises estimating based on the calibrationreferences and the test signals received when the plurality of probes isloaded by the seafood product.

In some embodiments, the controller drives each of the plurality ofprobes with the test signal individually, and while each probe isdriven, measures the received test signals at the one or more other testprobes.

In some embodiments, the controller comprises a variable frequencysource that generates the test signal, and wherein the test signalcomprises a plurality of test signals, each test signal having one of aplurality of frequencies.

In some embodiments, the plates are u-shaped, and the volume comprises au-shaped volume.

In some embodiments, the plurality of plates comprises four u-shapedplates.

In some embodiments, the system further comprises: an electromagneticshield surrounding an outer periphery of the plurality of plates thatsubstantially confines electromagnetic fields generated by the pluralityof plates to the volume defined by the plurality of plates.

In some embodiments, the plurality of plates are mounted onnon-conducting standoffs that provide galvanic isolation between theshield and the plurality of plates.

In some embodiments, the seafood product comprises a lobster, andwherein the plurality of probes are arranged for contact on an undersideof a tail of the lobster.

In some embodiments, the controller: measures relative impedance oftissue occupying space between the first probe and the one or more otherprobes of the plurality of probes; generates a profile of tissueimpedance along the plurality of probes; and estimates the physicalcharacteristic of the seafood product based on a gradient of theprofile.

According to a further aspect of the present invention, there isprovided a handheld device for estimating a physical characteristic of aseafood product comprising the system according to the aspect of thepresent invention described above.

According to yet another aspect of the present invention, there isprovide a method comprising: reading an ID from a Radio FrequencyIdentification (RFID) tag associated with a seafood product with anelectromagnetic resonant circuit; determining a loading effect of theseafood product on the electromagnetic resonant circuit when loaded bythe seafood product; estimating a physical characteristic of the seafoodproduct based on the loading effect of the seafood product; andassociating the ID from the RFID tag associated with the seafood productwith information relating to the estimation of the physicalcharacteristic of the seafood product.

In some embodiments, associating the ID from the RFID tag associatedwith the seafood product with information relating to the estimation ofthe physical characteristic of the seafood product comprises at leastone of: transmitting, via the electromagnetic resonant circuit, theinformation relating to the estimation of the physical characteristic ofthe seafood product to the RFID tag associated with the seafood productfor storage on the RFID tag; and storing the information relating to theestimation of the physical characteristic of the seafood product in adatabase, such that the information is associated in the database withthe ID of the RFID tag

In some embodiments, the electromagnetic resonant circuit comprises anantenna, and wherein determining the loading effect of the seafoodproduct on the electromagnetic resonant circuit comprises at least oneof: determining a change in impedance of the antenna between an unloadedstate and when loaded by the seafood product; determining a phase angleof a standing wave ratio (SWR) of the antenna; and determining a changein the gain of the antenna between the unloaded state and when loaded bythe seafood product.

In some embodiments, the method further comprises: reading the RFID tagto retrieve the information relating to the estimation of the physicalcharacteristic of the seafood product from the RFID tag associated withthe seafood product; and sorting the seafood product into one of atleast two grades based on the information retrieved from the RFID tag.

In some embodiments, the information relating to the estimation of thephysical characteristic of the seafood product comprises a grade of theseafood product; and sorting the seafood product comprises sorting theseafood product based on the grade of the seafood product stored on theRFID tag.

In some embodiments, operating frequency of the electromagnetic resonantcircuit is in a range of about 1 MHz to about 100 MHz.

In some embodiments, the method further comprises: determining a weightof the seafood product, wherein estimating the physical characteristiccomprises estimating the physical characteristic based on the loadingeffect and the weight of the seafood product.

In some embodiments, the method further comprises: maintaining thedatabase such that for each seafood product the database maintains arecord of the ID of the RFID tag associated with the seafood product andat least one of: the loading effect of the seafood product and theestimated physical characteristic of the seafood product.

In some embodiments, the method further comprises: performing linearregression on the loading effect to determine a linear relationshipbetween the loading effect and the physical characteristic.

In some embodiments, the method further comprises: determining athreshold as a boundary between quality grades; and determining aquality grade of the seafood product by comparing the loading effect tothe threshold.

In some embodiments, determining the threshold comprises performing adata mining algorithm.

In some embodiments, the method further comprises: calibrating by:determining a loading effect on the electromagnetic resonant circuit fora calibration seafood product with a known physical characteristic; andadjusting a function for estimating the physical characteristic based onany discrepancy between the known physical characteristic and thephysical characteristic estimate based on the determined loading effectfor the calibration seafood product.

In some embodiments, the seafood product comprises a plurality ofspecimens.

According to still another aspect of the present invention, there isprovided a system comprising: an electromagnetic resonant circuit; acontroller, functionally connected to the electromagnetic resonantcircuit, that: reads an ID from a Radio Frequency Identification (RFID)tag associated with a seafood product with the electromagnetic resonantcircuit; determines a loading effect of the seafood product on theelectromagnetic resonant circuit when the electromagnetic resonantcircuit is loaded by the seafood product; estimates a physicalcharacteristic of the seafood product based on the determined loadingeffect of the seafood product; and associates the ID from the RFID tagassociated with the seafood product with information relating to theestimation of the physical characteristic of the seafood product.

In some embodiments, the controller associates the ID from the RFID tagassociated with the seafood product with information relating to theestimation of the physical characteristic of the seafood product byperforming at least one of the following steps: transmitting, via theelectromagnetic resonant circuit, the information relating to theestimation of the physical characteristic of the seafood product to theRFID tag associated with the seafood product; and storing theinformation relating to the estimation of the physical characteristic ofthe seafood product in a database, such that the information isassociated in the database with the ID of the RFID tag.

In some embodiments, the electromagnetic resonant circuit comprises anantenna, and wherein the controller determines the loading effect of theseafood product on the electromagnetic resonant circuit by determiningat least one of: a change in impedance of the antenna between anunloaded state and when loaded by the seafood product; a phase angle ofa standing wave ratio (SWR) of the antenna; and a change in the gain ofthe antenna between the unloaded state and when loaded by the seafoodproduct.

In some embodiments, the system further comprises: an RFID readercomprising a second electromagnetic resonant circuit configured to readthe RFID tag associated with the seafood product to retrieve theinformation relating to the estimation of the physical characteristic ofthe seafood product; and a grader, functionally connected to the RFIDreader, configured to sort the seafood product into one of at least twogrades based on the information retrieved from the RFID tag.

In some embodiments, the information relating to the estimation of thephysical characteristic of the seafood product comprises a grade of theseafood product; and sorting the seafood product comprises sorting theseafood product based on the grade of the seafood product stored on theRFID tag.

In some embodiments, operating frequency of the electromagnetic resonantcircuit is in a range of about 1 kHz to about 100 MHz.

In some embodiments, the system further comprises: a weight scale,functionally connected to the controller, configured to determine aweight of the seafood product, wherein the controller estimates thephysical characteristic by estimating the physical characteristic basedon the loading effect and the weight of the seafood product.

In some embodiments, the system further comprises: the database incommunication with the controller that for each seafood productmaintains a record of the ID of the RFID tag relating to the seafoodproduct and at least one of: the loading effect of the seafood productand the estimated physical characteristic of the seafood product.

In some embodiments, the controller performs linear regression on theloading effect to determine a linear relationship between the loadingeffect and the physical characteristic.

In some embodiments, the controller: determines a threshold as aboundary between quality grades; and determines a quality grade of theseafood product by comparing the loading effect to the threshold.

In some embodiments, the controller performs a data mining algorithm todetermine the threshold.

In some embodiments, the controller comprises a variable frequencysource.

In some embodiments, the system further comprises: a biologist stationconsole functionally connected to the controller, the biologist stationconsole allowing a user to enter a known physical characteristic of acalibration seafood product, wherein the controller: determines theloading effect of the calibration seafood product with the knownphysical characteristic on the electromagnetic resonant circuit; andadjusts a function for estimating the physical characteristic based onany discrepancy between the known physical characteristic and thephysical characteristic estimate based on the determined loading effectof the calibration seafood product.

In some embodiments, the seafood product comprises a plurality ofspecimens.

Other aspects and features of the present invention will becomeapparent, to those ordinarily skilled in the art, upon review of thefollowing description of the specific embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described in greater detailwith reference to the accompanying diagrams, in which:

FIG. 1 is a flowchart of an example of a method in accordance with anembodiment of the invention;

FIG. 2 is a plot of the frequency response of an electromagneticresonant circuit in an unloaded state and a loaded state in accordancewith an embodiment of the present invention;

FIG. 3 is a block diagram of a system in accordance with an embodimentof the present invention;

FIG. 4 is a schematic of an electromagnetic resonant circuit inaccordance with an embodiment of the invention;

FIG. 5 is a flowchart of an example of another method in accordance withan embodiment of the invention; and

FIG. 6 is a schematic of an electromagnetic circuit in accordance withan embodiment of the invention.

DETAILED DESCRIPTION

Various systems and methods for non-invasive estimation of one or morephysical characteristics of seafood products such as lobsters and othercrustaceans, such as scallops, crabs, mussels and sea urchins areprovided. Embodiments of the present invention may provide for onlinephysical characteristic estimation at typical production speeds and/orgrading and separation of low and high meat yield seafood products attypical production rates at any stage of seafood processing. Forexample, some embodiments of the present invention are used at typicalproduction rates of 90 crustaceans per minute, with peak rates of closeto 120 crustaceans per minute. Other embodiments may be suitable forproduction rates higher or lower than these typical average and peakrates.

Some embodiments of the invention exploit the fact that the resonantfrequency and amplitude of an electromagnetic resonant circuit willchange when the circuit is “loaded” with an object that interacts withthe electromagnetic field generated by the circuit. That is, when anobject, such as a lobster with a particular amount of water held withinits internal structure, is exposed to the electromagnetic fieldgenerated by the circuit, the electromagnetic field will be altered byinteraction with the object, and the resonant frequency and amplitude ofthe oscillation in the loaded circuit will change depending on theproperties of the object.

In general, any additional loading of the resonant circuit will resultin a reduction of both the resonant frequency and amplitude of theoscillation in the circuit.

In some embodiments, the phase of a signal at the resonant frequency ofthe electromagnetic resonant circuit, relative to the phase of an inputsignal used to drive the circuit may be used to facilitate estimation ofa property of a seafood product under test, as the properties of aseafood product, such as tissue water content, may affect the phase ofan electromagnetic resonant circuit when the circuit is loaded with theseafood product.

Salt water is a relatively good conductor of electromagnetic energy, andtherefore an object composed of a relatively high percentage of saltwater may load the circuit, i.e., change the impedance of the circuitand hence the resonant amplitude and frequency, less than an object witha relatively low percentage of salt water. Accordingly, the change inresonant frequency and amplitude of a resonant circuit in a loaded andan unloaded state may indicate the water content of the object that ispresented as a load to the circuit.

A post-molt lobster will have a higher ratio of extracellular water tointracellular water in its internal structure compared to that of aninter-molt or pre-molt lobster due to the amount of water retained by apost-molt lobster within the new soft shell to fill it out. At certainfrequencies, extracellular water will more easily conduct electricitycompared to intracellular water, so a lobster with a high ratio ofextracellular water to intracellular water (a post-molt lobster) willpresent a different load to a resonant circuit than a lobster with alower ratio (an inter-molt or pre-molt lobster).

RFID readers and tags operate over a wide range of frequencies, howeverseveral of these frequencies are within a range, as described herein,that may be suitable to detect meat yield in seafood products, such aslobsters or other crustaceans.

In some embodiments, a Radio Frequency Identification (RFID) tag isassociated with the seafood product under test, and an electromagneticresonant circuit is implemented as part of an RFID reader that isoperable to estimate a physical characteristic of the seafood productbased on the loading effect of the seafood product on theelectromagnetic resonant circuit and to transmit information relating tothe estimated physical characteristic to the RFID tag associated withthe seafood product. The information relating to the estimated physicalcharacteristic transmitted to the RFID tag may then be retrieved fromthe RFID tag by RFID readers at later stages of processing, withoutrequiring that the later RFID readers be operable to estimate thephysical characteristic, as they can simply retrieve the informationfrom the tag.

In some embodiments, rather than storing the information relating to theestimated physical characteristic on the RFID tag, the information maybe stored in a database and associated with the ID of the RFID tag, sothat RFID readers at later stage of processing can read the ID of theRFID tag and retrieve the information relating to the estimated physicalcharacteristic from the database using the ID of the RFID tag. In theseembodiments, the RFID may not have memory for storing the informationrelating to the estimated physical characteristic.

In some embodiments, the information relating to the estimated physicalcharacteristic may be both stored in a database and transmitted to theRFID tag for storage on the tag.

In some embodiments, for example, a lobster is tagged with an RFID tagin the form of a passive tag with some on-chip memory, for example. Whenan RFID reader that includes the electromagnetic resonant circuitinterrogates the tag, it receives information about the identity of thatlobster, but some of the energy will be absorbed by the tissue of thelobster, thereby producing a loading effect on the electromagneticresonant circuit that is a part of the RFID reader, for example,resulting in a change of impedance in the circuit that is detectablefrom the RFID reader. This change in impedance within the field of theRFID reader can be sensed and used to estimate a physical characteristicof the lobster, for example the relative meat yield of the lobster. Thisinformation relating to the estimate of the physical characteristic canthen be pushed by the RFID reader to the on-chip memory on the passiveRFID tag attached to that lobster. In these embodiments, the RFID tagcarries both information relative to the identification of the lobsteras well as its estimated meat yield with no additional sensing hardware(other than the RFID reader).

It should be understood that the electromagnetic resonant circuit thatis included as part of an RFID reader as described herein can be used asa source of radio frequency (RF) energy that can be loaded by a seafoodproduct. The loading effect of the seafood product on the resonantcircuit may be used to estimate a physical characteristic of the seafoodproduct using the “slope” algorithm as described herein, or anyalgorithm in which the loading effect of the seafood product can becorrelated with a physical characteristic.

An example of a method for non-invasive estimation of a physicalcharacteristic of a seafood product in accordance with an embodiment ofthe present invention will now be described with reference to FIG. 1.

The method 110 begins at step 112, in which a reference peak resonantfrequency F_(resonant) _(—) _(ref) and reference peak resonant amplitudeA_(resonant) _(—) _(ref) of an electromagnetic resonant circuit in anunloaded state are determined. This step may be performed as an initialcalibration step with the result being stored for subsequent access,periodically during operation of an estimation system, or each time thephysical characteristic is to be estimated, for example.

In step 114, a minimum peak resonant frequency F_(resonant) _(—) _(min)and peak resonant amplitude A_(resonant) _(—) _(min) at F_(resonant)_(—) _(min) of the electromagnetic circuit are determined when thecircuit is loaded by a seafood product, such as a lobster.

In step 116, an estimate of a physical characteristic of the seafoodproduct is determined as a function of a slope defined by:

(A_(resonant) _(—) _(ref)−A_(resonant) _(—) _(min))/(F_(resonant) _(—)_(ref)−F_(resonant) _(—) _(min)).  (1)

The physical characteristic may include the refractive index and/or meatyield of the seafood product, for example.

In some embodiments, F_(resonant) _(—) _(ref) and A_(resonant) _(—)_(ref) are determined by sequentially applying a plurality of excitationfrequencies to the resonant circuit while it is unloaded and measuringthe amplitude and frequency of an output of the resonant circuit foreach excitation frequency to determine the peak amplitude and frequency,i.e., the resonant frequency and resonant amplitude.

Similarly, in some embodiments, F_(resonant) _(—) _(min) andA_(resonant) _(—) _(min) are determined by applying a plurality ofexcitation frequencies to the resonant circuit while it is loaded withthe seafood product and measuring the amplitude and the frequency of theoutput of the resonant circuit for each of the excitation frequencies.The plurality of excitation frequencies may be applied to the circuitmultiple times while the seafood product is exposed to theelectromagnetic field generated by the circuit. For example, the seafoodproduct may be moving on a processing plant belt so that it passesthrough the electromagnetic field generated by the resonant circuit sothat the orientation and location of the seafood product relative to theelectromagnetic field of the resonant circuit is changing while theplurality of excitation frequencies are being applied. Applying theplurality of excitation frequencies multiple times may allow for a moreaccurate determination of the minimum resonant frequency F_(resonant)_(—) _(min).

In some embodiments, the method 110 further comprises reading an ID froma Radio Frequency Identification (RFID) tag associated with the seafoodproduct with the electromagnetic resonant circuit and storinginformation relating to the estimation of the physical characteristic ofthe seafood product.

In some embodiments, storing the information relating to the estimationof the physical characteristic comprises storing the information in adata base and/or transmitting the information to the RFID tag associatedwith the seafood product for storage on the RFID tag.

In some embodiments, at a later stage of processing, an RFID readerreads the RFID tag associated with the seafood product, to therebyretrieve the ID of the RFID tag and/or the information relating to theestimation of the physical characteristic of the seafood product fromthe RFID tag. The seafood product is sorted into one of at least twogrades based on the information retrieved from the RFID tag in someembodiments.

Although only one cycle of the method 110 is shown in FIG. 1, theillustrated operations may be repeated as lobsters pass an estimationsystem on a production line. Other embodiments may include additionaloperations that have not been explicitly shown, such as grading and/orsorting operations based on meat yield estimates.

FIG. 2 provides a plot of the frequency response of an electromagneticresonant circuit in an unloaded state and in a loaded state when loadedby a lobster or other object in accordance with an embodiment of thepresent invention. In the plot shown in FIG. 2, the x-axis represents avaractor control voltage for a varactor-controlled oscillator. Adjustingthe varactor control voltage adjusts the oscillation frequency of avaractor-controlled oscillator in some embodiments of the invention.Accordingly, each of the illustrated varactor control voltagesrepresents an oscillation frequency of an input of the electromagneticresonant circuit.

The reference resonant peak 200 is decreased in amplitude and frequencyto a minimum resonant peak 202 when the resonant circuit is loaded bythe lobster. In the plot shown in FIG. 2, the plurality of excitationfrequencies are applied multiple times while the lobster is passedthrough the electromagnetic field of the resonant circuit. The peakresonant frequency for each application of the plurality of excitationfrequencies falls on the path 206 between reference resonant peak 200and the minimum resonant peak 202, because the position of the lobsterimpacts its effect on the resonance of the circuit. The slope 204defined by (1) between the reference resonant peak 200 and the minimumresonant peak 202 can be used as described herein to estimate thephysical characteristic of the lobster.

It should be noted that the example plot shown in FIG. 2 is forillustrative purposes only. Different frequency responses may beobserved, for example, for different resonant circuits operated underdifferent conditions and/or for different objects loading a resonantcircuit.

While the units for the y-axis of FIG. 2 are shown as mV, i.e., theoutput voltage of the resonant circuit, more generally any measurementthat corresponds to a change in resonant frequency and magnitude of theresonant circuit in an unloaded and a loaded state can be used, as thecalculated slope output is a relative measure between lobsters or otherseafood products under test. For example, in some embodiments, analog todigital converter (ADC) counts may be used, where there are a specificnumber of ADC counts per volt.

The plurality of excitation frequencies may be selected on either sideof the resonant frequency of the unloaded resonant circuit so that theresonant frequency of the unloaded resonant circuit falls within therange of excitation frequencies defined by the plurality of excitationfrequencies.

In general, the range of frequencies defined by the plurality ofexcitation frequencies is selected to include the range of minimum peakresonant frequencies F_(resonant) _(—) _(min) resulting from the normalphysical variation in the physical characteristic of a particularseafood product.

In some embodiments, a scanning frequency window of approximately 750kHz to 1 MHz about the unloaded resonant frequency is sufficient todefine an unloaded peak resonant amplitude and frequency and capture theshift in resonance when loaded. This range is an implementation specificdetail and the foregoing range is provided merely as an example.

If the seafood product causes the minimum peak resonant frequencyF_(resonant) _(—) _(min) to fall outside of the range of excitationfrequencies, F_(resonant) _(—) _(min) may not be accurately determined,and the determination of the slope and hence the estimation of thephysical characteristic may be inaccurate. The range of the plurality ofexcitation frequencies may be selected by running one or more sampleseafood products through the measurement process to ensure that therange of excitation frequencies includes the minimum resonant peakfrequencies of the sample seafood product(s).

The resonant circuit may be designed to have an unloaded resonantfrequency that is chosen based on the particular electrical propertiesof the seafood product that is to be measured. For example, in someembodiments, a resonant circuit with a resonant peak close to 20 MHz inair may be used for lobsters. However, there is a broad range offrequencies in which low and high meated crustaceans, such as lobsters,appear to have different impedances. These differences in impedanceswill result in a different shift in resonance for low and high meatedcrustaceans, and therefore can be used to evaluate meatedness. Forlobsters, resonant peaks as low as 75 kHz and as high as 100 MHz, may beused in some embodiments. The impact of using different resonantfrequencies has to do with the impedance of intra/extracellular water ofthe crustacean resulting in flow path differences of current through thetissue/water of the crustacean at different frequencies.

In some embodiments, a “calibration” step is performed in which aplurality of sample lobsters are run through the method shown in FIG. 1and then linear regression is used on the data from this samplepopulation to determine a linear relationship between the slopedetermined by (1) and the physical characteristic. The use of linearregression techniques for processing data is described, for example, inWalpole, R. E., Myers, R. H., “Probability and Statistics for Engineersand Scientists,” 5^(th) Ed., New York, 1993. Other techniques may alsoor instead be used.

In some embodiments, a threshold slope is determined and seafoodproducts having a slope above the threshold are determined to be“well-meated” product, while seafood products having a slope below thethreshold are determined to be “low meat yield” product. The thresholdmay thus be used to separate lobsters into one of two “grades”.

Other embodiments may use two thresholds: a lower threshold and an upperthreshold. Seafood products having a slope above the upper threshold aredetermined to be “high meat yield” product, while seafood productshaving a slope between the lower threshold and the upper threshold aredetermined to be “medium meat yield” product, and seafood productshaving a slope below the lower threshold are determined to be “low meatyield” product.

As will be apparent, a number of thresholds may be chosen to implementvirtually any desired grading or sorting “granularity”.

The threshold or thresholds may be weight/size dependent. For example,lobsters are commonly categorized based on weight in to categories, suchas canners, chix, quarters and selects. The threshold or thresholds foreach of the categories may be different, since the relationship betweenthe slope determined by (1) and the physical characteristic may verydepending on the physical size/weight of the lobster.

In some embodiments, the reference peak resonant frequency F_(resonant)_(—) _(ref) and the reference peak resonant amplitude A_(resonant) _(—)_(ref) are determined based on a rolling average of a particular numberof unloaded resonant frequency and amplitude measurements. For example,F_(resonant) _(—) _(ref) and A_(resonant) _(—) _(ref) may be the averageof five measurements of the unloaded peak resonant frequency andamplitude.

FIG. 3 is an illustration of a block diagram of a system 350 inaccordance with an embodiment of the present invention. It should beappreciated that the system 350 is intended solely for the purposes ofillustration, and that other embodiments may include further, fewer, ordifferent components interconnected in a similar or different mannerthan explicitly shown.

The system 350 includes a sensor 300 functionally connected to acontroller 302 at 312.

The sensor 300 is located beneath and in close proximity to a processorbelt 304 that carries a lobster 308 on its top surface in the exampleshown, although other arrangements are also possible.

In some embodiments, belt 304 is made of plastic, such as high densitypolyethylene (HDPE) with no metal content, as metal may interfere withsensor 300.

Salt water may also interfere with the measurements taken by sensor 300,i.e. salt water may reduce the impedance presented by belt 304, andtherefore in some embodiments belt 304 is rinsed continuously with freshwater to maintain a relatively constant impedance.

A trigger 306 is located near the top surface of the belt 304 before thesensor 300 such that the passage of the lobster 308 on the belt 304 willtrip the trigger 306. The trigger 306 is functionally connected to thecontroller 302 at 314.

In some embodiments, the trigger 306 includes an optical trigger. Ingeneral, the trigger 306 may be any type of sensor that detect thearrival of a lobster or other seafood product at a location ahead of thesensor 300. Although shown separately in FIG. 3, the trigger 306 couldpotentially be integrated into a single device with the controller 302and/or the sensor 300.

The controller 302 has an output 318 that is functionally connected to agrader 316 that is located downstream of the sensor 300 with respect tothe direction of the belt 304.

In some embodiments, the system 350 also includes a hub 322 that isfunctionally connected to the controller 302 at 334. The hub 322 is alsofunctionally connected to a biologist station console 332 at 346 and toa server 320 at 336 and 342.

In some embodiments, the server 320 includes a listener 324, a database326 and an interface 328. The listener 324 is functionally connected tothe hub 322 at 336, and is also functionally connected to the database326 at 338. The interface 328 is functionally connected to the database326 at 340, and may be functionally connected to the hub 322 through theoutput 342 of the server 320.

The Listener 324 may be implemented as a software algorithm that managesdata transfer from biologist station console 332 and controller 302, andstores the data in database 326, for instance.

In some embodiments, the interface 328 of the server 320 is implementedas a webpage such as a dynamic personal home page (PHP) webpage.

In some embodiments, a remote user system 330 is functionally connectedto the interface 328 of the server 320 at 344.

In operation, as the lobster 308 is moved along by the belt 304, thetrigger 306 is tripped by the lobster 308 prior to reaching the sensor300. The trigger 306 signals the controller 302 through an output at 314that the lobster 308 is approaching the sensor 300. The controller 302determines a reference peak resonant frequency F_(resonant) _(—) _(ref)and amplitude A_(resonant) _(—) _(ref) of the sensor while the sensor isin an unloaded state, by driving an input of the sensor at 312 with aplurality of excitation frequencies and measuring an amplitude of anoutput of the sensor at 312 at each of the excitation frequencies.Although shown as a single connection 312 in FIG. 3, a separate inputand output may be provided between the sensor 300 and the controller302.

The reference peak and amplitude need not necessarily be determined bythe controller 302 each time the trigger 306 detects a lobster 308approaching the sensor 300. For example, the controller 302 mightdetermine its references every few minutes. The references could then bestored in a memory (not shown) functionally connected to the controller302 and accessed by the controller 302 until new references are to bedetermined.

As the lobster 308 passes over the sensor 300 on the belt 304, theexcitation frequencies are applied again at least once to determine theminimum peak resonant frequency F_(resonant) _(—) _(min) and amplitudeA_(resonant) _(—) _(min).

The slope defined by (1) may then be used to estimate a physicalcharacteristic such as meat yield of the lobster 308. The slope and/orthe physical characteristic may be passed on by the controller 302through an output at 318 to the grader 316 for sorting purposes. Thephysical characteristic of the lobster 308 may be estimated indirectlyby first using a linear regression of the slope defined by (1) vs. RI todetermine the RI of the lobster. Correlation between RI and meat yieldis quite strong (in some cases the correlation between RI and meat yieldis r˜0.93). Therefore, in some embodiments, when the physicalcharacteristic of concern is meat yield, a threshold for distinguishingbetween grades of meat yield may be based on RI alone.

The proximity of the sensor 300 to the lobster 308 can affect thequality of measurements that can be made. For example, if the sensor 300is located too far from the lobster 308, the signal to noise ratio ofthe output at 312 of the sensor will be low, since the lobster 308 maypass through only the fringes of the electromagnetic field of the sensor300. Furthermore, the consistency of the distance between the lobster308 and the sensor 300 may be important, because differences in thisdistance can cause variations in the measurements.

In some embodiments, the sensor 300 is located within one or two inchesof the bottom of the belt 304.

In general, the distance between the sensor 300 and the belt 304 is animplementation specific detail that may depend, for example, on thesensitivity of the sensor 300, the material of the belt 304, the stateof the belt 304 (for example: salty, wet, dirty), the gap size betweenthe neighbouring co-planar plates (406 and 408) for a sensor such asthat illustrated in FIG. 4, and/or the seafood product under test.

Accordingly, oscillations in the processing belt 304 may causemeasurement errors. For this reason, a “chute-style” system may beinstead used, where the lobster 308 slides down a rigid chute that is aset distance from the sensor 300, which could eliminate the errorsassociated with oscillations of the belt 304.

In some embodiments, a tensioning roller may be used underneath the belt304 to maintain a relatively constant tension in the belt to reduceoscillations and static variations in the distance between the belt 304and the sensor 300.

In addition, inconsistencies in the electrical properties of the beltalong its length can affect the measurements. An old belt that ispartially wetted with salt water can cause large variations in themeasurements, for example.

In some embodiments, the belt 304 is sprayed and rinsed with fresh waterto reduce inconsistencies in the belt conditions.

In some embodiments, the system includes a weight scale that measuresthe weight of the lobster 308 and reports the weight to the controller302 for use in estimating the physical characteristic of the lobster308, i.e., the same slope for lobsters of different weights may indicatea different physical characteristic. The weight scale may be included aspart of the grader 316, for instance.

In some embodiments, an RFID tag (not shown) storing information relatedto the ID of the lobster 308 is attached to the lobster and the sensor300 is part of an RFID device that includes an electromagnetic resonantcircuit that is loaded by the lobster 308 as it passes over the sensor300.

In some embodiments, the controller is operable to estimate a physicalcharacteristic of the lobster 308 based on the loading effect of thelobster on the electromagnetic resonant circuit of the sensor 300 andstore the information relating to the estimated physical characteristicon the RFID tag by transmitting the information to the RFID tag, via theelectromagnetic resonant circuit of the sensor 300, for storage on thetag in addition to the information already stored on the tag related tothe ID of the lobster and/or transmitting the information to the server320 for storage in the database 326.

In some embodiments, the controller 302 reports the slope and/or theestimate of the physical characteristic and/or the raw resonantmeasurements, i.e. r F_(resonant) _(—) _(ref), A_(resonant) _(—) _(ref),F_(resonant) _(—) _(min) and A_(resonant) _(—) _(min) for each lobster308 to the server 320 through the hub 322 via the input/output at 334and the output at 336. Each lobster 308 may be assigned a lot and binnumber by the grader 316, and the lot and bin number may also becommunicated to the server 320. The listener block 324 receives the datafrom the output at 336 of the hub 322 and stores the data in thedatabase 326 through its output at 338.

In some embodiments, the database 326 is a MySQL database.

The data in the database 326 can be accessed by the remote user system330 on the internet via the interface 328 using the input/output 344.

In some embodiments, the remote user system 330 can also sendinstructions to the controller 302 through the interface 328 and the hub322 via the input/output 344, the output 342 and the input/output 334.

In some embodiments, the controller 302 is implemented as a personalcomputer with a central processing unit (CPU) card, an Ethernet card,and analog card, a power regulator card, and a custom processing card.

The Ethernet card provides an Ethernet interface from the controller tothe other Ethernet devices in the system, and allows for remote controlof the controller 302.

The analog card provides an interface between the digital CPU card andthe sensor 300 in embodiments in which an analog sensor is implemented.The analog card converts a digital number to an analog voltage andvice-versa. It may also have optically isolated digital inputs foroptical gate signals, such as the output of the trigger 306, andmechanical relays for switching LEDs or gating power to equipment. Theanalog card is controlled by embedded code to indicate when a triggerhas occurred, to output an analog drive signal to the custom card, andmeasure the analog response from measurement circuitry on the customcard. The mechanical relays may be used to light the LEDs if a faultcondition exists and to gate power to the custom card.

The power regulator card provides conditioning and regulation of inputpower from an external DC source. This card allows the input voltage tovary from 6 VDC to 36 VDC without affecting the processes running insome embodiments. It also provides robustness to power line noise.

In some embodiments, the custom card may contain a varactor-controlledoscillator and measurement circuitry of the custom card may beimplemented as a vector volt meter (VVM). Changing the analog drivesignal voltage applied to the varactor, such as by applying asaw-tooth-like analog waveform, modifies the frequency of the driveoscillator. The VVM measures the relative magnitudes of the input andthe output at 312 of the sensor 300, and, in some embodiments, theirrelative phase. A digital to analog interface card that is capable ofgenerating the plurality of analog excitation frequencies to be appliedto the input of the sensor 300 may also be provided in the controller302.

In some embodiments, the custom card includes a multi-frequency chip,such as a direct digital synthesis digital-to-analog converter (DDS DAC)that is capable of receiving a multi-bit digital input and generating aspecific frequency for each multi-bit input. In general, any analogsignal source may be used for generating a plurality of excitationfrequencies that will encompass the loaded and unloaded resonant peaksof the sensor 300.

In some embodiments where a varactor controlled oscillator is used inthe controller 302, a “saw-tooth-like” wave form may be used to drivethe varactor, so that the excitation frequency of the input at 312 ofthe sensor 300 is repeatedly “swept” over a specific range offrequencies.

The processing capability of the controller 302 may be implemented usinga CPU, an application specific integrated circuit (ASIC) or a logicdevice such as a field programmable gate array (FPGA) or a programmablelogic device (PLD). In general, the processing capability of thecontroller 302 might be implemented using hardware, software, firmwareor combinations thereof.

Varactors are generally highly non-linear, and therefore amulti-frequency chip may offer better performance than thevaractor-based implementations, since the output frequency of themulti-frequency chip can be accurately controlled by its digital inputs.

In some embodiments, the biologist station console 332 allows abiologist or other qualified technician or user to enter pertinentbiological data from sampled lobsters, which data can then be sent toand stored in the database 326. The biological data may include arefractive index from a sampled lobster, which can provide continuouscalibration data for the sensor 300. For example, if the refractiveindex of a sampled lobster is determined by another system or device(not shown) and entered into the database 326 by a biologist using thebiologist station console 332 on the processing line, the sampledlobster can then be placed on the belt 304 and passed over the sensor300 as a calibration lobster so that the physical characteristicestimation algorithm executed by the controller 302 can be adjusted tocorrespond to the refractive index determined by the biologist if thereis any discrepancy.

The biologist is also able to view results and reports from theinterface 328 from the biologist station console 332.

In some embodiments, much of the processing done by the controller 302is carried out by a 32 bit commercially available processor. Thisprocessor is in control of all of the frequency scanning requirements ofthe system. This change allows control of a 32 bit digital frequencyoscillator chip, i.e. a multi-frequency source such as a controlledoscillator, through Serial Peripheral Interface (SPI) communications.

The frequency oscillator chip might have the ability of generatingsinusoidal voltage outputs from DC (0 Hz) to approximately 70 MHz in0.04 Hz steps, for example. Such a chip could replace thevaractor-controlled oscillator of the system described above as a meansof having a more broad frequency sweeping capability and more accuratecontrol over the specific operating frequency of the sensor 300.

The processor could also be used to read the VVM output voltages (phaseand magnitude outputs), with a 16 bit 500 kSPS analog to digitalconverter (ADC) over the SPI interface, for instance.

When such a processor is used, the CPU card of the controller 302, whichused to do all of the system processing, now serves primarily as thenetwork communications router for the system. However, the CPU card canstill be used to run data mining models on the measured values returnedfrom the processor as well as the grader 316 system. This will beexplained in more detail below.

At boot, or during idle time, the processor may do a wide rangefrequency sweep of the current operating conditions to determine exactlywhere the resonant peak of the sensor 300 is located (in frequency). Itdoes this by commanding the frequency oscillator chip to start at a 15MHz frequency and step all the way to 25 MHz in 1.5 kHz steps in oneembodiment. During this sweep, the voltage output of the VVM ismonitored in order to locate the highest magnitude value. The largestmagnitude of the entire sweep is detected as the resonant peak of thesensor 300.

After the initial air sweep the processor will wait until the controller302 detects a trigger from the trigger 306. When the controller 302detects this event it informs the processor of the presence of anapproaching lobster 308 on the belt 304, illustratively via a TCPconnection. The processor then performs a 1.5 MHz sweep centered aroundthe resonant peak in 18.75 kHz steps. This accurately detects thefrequency of the resonant peak in “air” (no lobster present).

The processor centers its frequency window about this peak frequency andstarts its scanning. The scan may consist of a fixed number of frequencysweeps (illustratively ˜80), over which the VVM voltages are measured atmultiple identical frequency values (illustratively ˜100 frequencyvalues per sweep). This data could be stored in local memory of theprocessor during each sweep. If the specific lobster 308 that is beingscanned is detected as a calibration lobster (based on a triggeringevent from the biologist station console 332), the entire sweep data istransmitted, again illustratively via TCP, to the Listener 324 to bestored in the database 326 for future analysis. On regular lobsters(non-calibration), a delay equal to the length of the TCP transmit timecan be added at the end of each sweep so that the measurement resultsare similar between calibration lobsters and non-calibration lobsters.

When a scan is completed, and before transmitting data over TCP orduring the delay, the processor may command the frequency oscillatorchip to set the frequency back to the initial frequency of the sweeprange. This is done to help avoid issues of the system instantaneouslychanging from a high frequency to a low frequency at the start of eachsweep.

While sweeping, the processor computes a moving average filter,illustratively a five point filter, on the data to clean it up anddetermine a more accurate peak location for the current sweep. Thesepeak values can be stored in an array in memory for later processing.When the scan is complete and all of the peak locations of each sweephave been stored in memory, the processor calculates all statistics tobe used in the slope algorithm. Once these statistics are computed theprocessor computes the actual slope value defined by (1). Finally, theprocessor may send all of the calculated statistic values and the slopevalue to the listener 324 and they are stored in the database 326.

Once a lobster activates the trigger 306, the controller 302 notifiesthe processor possibly with a TCP communication. When the processor hasfinished scanning, it returns the calculated values to the controller302. The controller 302 keeps this data in memory until it has receivedthe weight information from the grader 316 in some embodiments. Once theweight information is received, the controller 302 takes all of thecombined data that it has received about this lobster and runs itthrough a data mining model to get an estimate of RI.

Based on this estimate, the controller 302 may give the lobster aclassification value and send that value to the grader 316 so that itmay be placed in the correct bin.

If the current lobster was determined to be a calibration lobster, basedon an input from the biologist station console 332 communications and atiming window for instance, the controller 302 conducts furtherprocessing after the transmission to the grader 316 is completed. Sincethe lobster is a calibration lobster, the controller 302 knows itsmeasured RI value (transmitted from the biologist station console 332).The controller 302 attaches this value to the other measured statisticsand adds it to a global array of a previous number of lobstercalibration data. The controller 302 then executes its data mining codeon this global array to update the current data mining model. Allsubsequent lobsters that are scanned have their quality judged based onthis current model (which changes once a new calibration lobster isentered).

An example of a data mining algorithm that may be used in accordancewith an embodiment of the present invention is a Stochastic GradientBoosting algorithm, as described in Jerome H. Friedman, “StochasticGradient Boosting”, Computational Statistics & Data Analysis, v. 38 n.4, p. 367-378, 28 Feb. 2002.

In some embodiments, the data mining algorithm may be trained using onlya subset of all of the data collected from calibration lobsters. Forexample, only the last 100 calibration lobsters may be used to train thealgorithm. This may allow the model to track changes over time. Theselection of the size of the training “window”, e.g. 100 lobsters, is animplementation specific window. Statistical analysis on past data, forexample, a previous season's entire data set, may be used to optimizethe size of the training window.

An embodiment of the sensor 300 is shown in detail in FIG. 4. In theembodiment shown in FIG. 4, the sensor 300 includes two substantiallyco-planar plates 406,408, an inductor 404, a “tickler” coil 400 and a“sense” coil 402.

The two co-planar plates 406,408 are located a short distance apart andfunction as a planar capacitor. The two co-planar plates 406,408 arerespectively connected to the ends of the inductor 404, which is shownas a coil inductor in FIG. 4.

The “tickler” coil 400 is located at one end of the inductor 404 and the“sense” coil 402 is located at the other end of the inductor 404 so thatthe “tickler” coil and the “sense” coil are inductively coupled to theinductor 404.

The “tickler” coil 400 is connected to the input 311 of the sensor 300and the “sense” coil 402 is connected to the output 313 of the sensor300. The input 311 and the output 313 are shown in FIG. 3 as a singleconnection 312.

The components of the sensor 300 shown in FIG. 4 form a resonant tankcircuit that will have a specific resonant peak in air that depends onthe dimensions and properties of the individual components. The designof such a circuit to have a desired resonant characteristic will beapparent to those skilled in the art.

In operation, when an excitation frequency is applied to the input 311,the “tickler” coil 400 couples the excitation frequency to the inductor404 and the frequency response of the tank circuit is coupled to the“sense” coil 402, and hence to the output 313 of the sensor 300. Theoutput 313 of the sensor will be at a peak when the excitation frequencyis equal to the resonant frequency of the tank circuit. For example, seethe resonant peak 200 in FIG. 2. The two co-planar plates 406,408function as a planar capacitor, and therefore an electric field isgenerated between the two plates. This electric field extends above theupper surface of the co-planar plates 406,408, and when a lobster passesabove the sensor it will interact with this electric field. Thisinteraction will effectively load the tank circuit with the impedance ofthe lobster and the resonant peak of the tank circuit will change asdescribed above with reference to FIG. 2.

In some embodiments, the two co-planar plates are implemented withaluminum plates that are ⅛″ thick, four inches long and 18 inchesacross. The plates 406,408 are arranged so that they are separated by aconstant one inch gap along one of their long edges. The plates 406,408are arranged above the inductor 404 and the plates 406,408 and theinductor 404 are mounted in a high density polyethylene (HDPE) platformthat can be installed under the processing belt 304 shown in FIG. 3.

In some embodiments, the inductor 404 is implemented with a coil with adiameter of approximately 2.25 inches and a length of approximately 6.5inches with nine turns. The coil may be mounted in a sealed canister,with the “tickler” coil 400 and “sense” coil 402 located within thesealed canister.

The inductor 404 and the plates 406,408 form a resonant tank with a veryhigh quality factor Q. For example, the Q of the tank circuit may be 150to 200.

In some embodiments, the resonant peak of the tank circuit is close to20 MHz in air.

While the foregoing embodiments have been described in the context ofnon-contact measurements, i.e., embodiments in which remote loading ofan electromagnetic resonant circuit by a seafood product is used toestimate a physical characteristic of the seafood product, embodimentsare not limited to non-contact measurements, nor are they necessarilylimited to estimation based on loading effect of the seafood product onan electromagnetic resonant circuit.

In some embodiments, a sensor comprising a plurality of plates or otherforms of probe may be brought into direct contact with a seafoodproduct, for example, on the underside of a tail of a lobster. A firstone of the probes may be driven with a test signal and the received testsignal at one or more of the other probes may be measured. The receivedtest signals at the one or more other probes may then be used toestimate a physical characteristic of the seafood product.

Contact of an electromagnetic resonant circuit with a seafood productmay cause the “squashing” of a resonant peak of the electromagneticresonant circuit, making resonant circuits potentially unsuitable forsome contact measurement-based embodiments. Accordingly, non-resonantcircuits may be used in some contact measurement-based embodiments togenerate the test signal(s) used to drive the probes that are contactedto the seafood product.

In some embodiments, the relative magnitude and phase between the testsignal driven to the first probe and the test signals received at theone or more other probes are measured, thus detecting the relativeimpedance of the lobster tissue occupying the space between the driveprobe and each sense probe. By combining the results of the measurementsmade for each individual probe, a profile of the impedance of the localtissue below the contact points of the probes can be determined. Byusing a plurality of probes contacted on, for example, the underside ofa lobster tail, the profile of the impedance of the local tissue depictsan “image” of the water-to-tail muscle in that region. For post-moltlobsters, this profile may depict significant water content between thetwo tail muscles, and thus a steep gradient in this profile curve. Thegradient may not be as significant in the case of pre-molt lobsters inwhich typically very little inter-muscle water exists. Thus, thegradient in these water-to-tail muscle profiles may be used as a methodto discern meat yield content in the lobster.

While the foregoing embodiments have been described in the context ofmeasurement of individual seafood products, such as lobsters,embodiments are not limited to determining the physical characteristicsof individual lobsters.

In some embodiments, the measurement system 350 may be implemented in acrate sensor form factor. That is, the measurement system 350 may beused to determine the average physical characteristic, for example meatyield, of a crate containing multiple specimens of a particular seafoodproduct, such as lobster. For example, in some embodiments, the plates406, 408 in the embodiment shown in FIG. 4 may be implemented as“U-shaped” plates with three substantially planar surfaces, and a crateof seafood product may be placed in the open well of the “U” formeasurement. In such an embodiment, each crate of seafood product may beplaced into the U-shaped sensor arrangement by hand or any othermechanism, and the sensor could be used wharf-side to evaluate thephysical characteristics of crates of seafood product that areavailable.

Evaluating a physical characteristic of a crate of seafood product mayallow a seafood processor to select the “grade” of seafood product thatthey are interested in purchasing, rather than having to purchase acrate of seafood product and then individually evaluate each lobster,although a crate scanner might be used for initial selection of a groupof products for purchase, and those product could be processedindividually by an online scanning system for specific sorting.

While the sensor 300 described above with reference to FIG. 4 is aresonant circuit with two co-planar plates 406, 408, embodiments are notlimited to resonant sensor arrangements with only two plates. Forexample, a method 500 in accordance with an embodiment will now bedescribed with reference to the flowchart shown in FIG. 5, in which asensor with multiple plates is used to determine a physicalcharacteristic of a crate of seafood product.

Method 500 begins at step 502, in which a test signal is applied to oneor more of a plurality of spatially separated plates while the platesare loaded by a seafood product, which may be a crate containingmultiple specimens of a particular seafood product, such as lobster.

In step 504, received test signals are measured at another plate,illustratively at two or more of the other plates.

In step 506, a physical characteristic of the seafood product, e.g. anaverage meatedness of the crate of lobster, is estimated as a functionof calibration references, which might be determined while the platesare not loaded by a seafood product, and the received test signals inthe loaded state. Differences between the measured signals and thereference signals may be used to distinguish between different grades.

FIG. 6 is a schematic of a multi-plate electromagnetic sensor circuit600 in accordance with an embodiment of the present invention. Thesensor circuit 600 may be used, for example, with the method illustratedin the flowchart of FIG. 5.

Sensor circuit 600 includes four spatially separated plates 601, 602,603, 604 that are “U-shaped” and arranged to define a volume into whicha crate of seafood product, generally represented at 605, can be placedfor measurement.

The operation of the sensor circuit 600 uses the principle of assessingthe physical properties of objects by measuring disturbances in an EMfield caused by the presence and positioning of these objects within theEM field.

The sensor circuit 600 may be controlled by a controller (not shown)that is similar to the controller 302 illustrated in FIG. 3.

The controller creates radio-frequency (RF) oscillations for driving theplates 601, 602, 603, 604 and detects changes in the received RF signalat the plates due to the EM field disturbance caused by the crate ofseafood product 605.

In some embodiments, the plates 601, 602, 603, 604 are surrounded ontheir outer periphery by an outer shell (not shown) that acts as shieldso that the EM field generated by applying test signals to the plates isgenerally confined to the volume defined by the plates. In theseembodiments, the plates 601, 602, 603, 604 might be mounted inside theshield on non-conducting standoffs that provide galvanic isolationbetween the shield and the plates. The plates are spaced apart and, insome embodiments, have rollers positioned between them to providesupport for the crate of seafood product 605.

By using multiple plates 601, 602, 603, 604, it is possible to measuredifferent depths into the crate 605. For example, by driving andmeasuring from neighboring plates (for example driving 601 and sensingon 602), the EM field generated may penetrate only a shallow amount intothe crate 605 (for example, measuring lobsters near the bottom of thecrate). However, by driving the end plate 601 and sensing from the plate604 at the opposite end of the sensor 600, the field penetration isdeeper into the crate 605 (for example, measuring lobsters closer to thetop of the crate).

The disturbance in the EM field is detected by comparing the signalsfrom the sensing plate in unloaded and loaded states. In both cases thedrive signal can be taken as a reference. In some embodiments, a VectorVolt Meter (VVM) is used to measure the driven and sensed signals. Thedrive signal is fed to one of the inputs of the VVM while the sensesignal is fed to another input of the VVM. The VVM has two output analogvoltage signals that represent the difference in magnitude and phasebetween its two input signals, thus qualifying the impedance of thetested object.

In some embodiments, driving and sensing with the plates 601, 602, 603,604 may be done over a range of frequencies. For example, test signalswith frequencies from 1 KHz to 50 MHz in steps of 5 KHz may be used insome embodiments.

In one particular embodiment, the controller (not shown) includes a mainboard (MB) that provides a digital communication interface with, forexample, a remote data server, and an analog board (AB) that interfaceswith the main board and the plates 601, 602, 603, 604 to drive and senseradio frequency signals using the plates.

In some embodiments, the MB passes digital data containing a requestedtest frequency to the AB via a serial peripheral interface (SPI) bus. ADirect Digital Synthesis Digital-to-Analog Converter (DDS DAC) receivesthe data and produces the RF signal that is further amplified and fed toone of the plates (for example plate 601) to produce an EM field in thesensor's test space, i.e. inside the volume defined by the plates). Thefield can be sensed by any of the other plates (for example, plate(s)602, 603 and/or 604) of the sensor 600 with the exception of the onethat is being driven at the moment.

In some embodiments, the VVM outputs are converted to digital form in ahigh-speed Analog-to-Digital Converter(ADC). The digital data containingresults (magnitude and phase) of the scan for the current frequency issent then to the MB via an SPI bus. In one embodiment, the MB runssoftware to store and analyze the scan data. The controller (not shown)may also include a display that indicates the result of the scan. Forexample, the controller may include a visual display that indicates theaverage meatedness of the seafood product in the crate 605.

Control of both EM field frequency and the drive-sense plate spacing mayallow the impedance of a test object, for example a crate of seafoodproduct, to be analyzed at different frequencies and at differentpenetration depths.

In some embodiments, the following pattern of driving and sensing isused:

Drive 601

Sense 602

Sense 603

Sense 604

Drive 602

Sense 601

Sense 603

Sense 604

Drive 603

Sense 601

Sense 602

Sense 604

Drive 604

Sense 601

Sense 602

Sense 603

The foregoing pattern results in multi-frequency graphs (for example, 1KHz to 50 MHz) for each “pair” of driven/sense plate arrangements.

In some embodiments, the magnitude of the sensed signals is used over abroad frequency range to discern the quality grade of a crate of seafoodproduct. For example, in some embodiments, the difference in magnitudeof the sensed signals in an unloaded and loaded state is used todistinguish between crates of high quality and low quality lobsters.

While the plates 601, 602, 603, 604 are shown as U-shaped plates in FIG.6, more generally a plurality of plates of any shape may be utilized todefine a volume into which a crate can be placed for measurement. Forexample, each of the “arms” of the plates 601, 602, 603, 604 might notbe connected to one another so that each plate is separated into threeseparate plates (a top or bottom and two sides) that may be driven andsensed independently of one another.

In some embodiments, one or more of the plates might be movable to“scan” different portions of the crate 605. For example, in oneembodiment, there may be one or more fixed plates and one or moremovable plates. In one particular embodiment, only one fixed plate andone movable plate are used.

While the foregoing embodiments utilize changes in the amplitude of theelectromagnetic response of resonant and non-resonant circuits toestimate a physical characteristic of a seafood product, otherdifferences in the electromagnetic response of resonant or non-resonantcircuit may be used in some embodiments. For example, some embodiments,may use the phase of the electromagnetic response, rather than, or inaddition to, the amplitude.

While the foregoing has been provided in the general context ofdetermining a physical characteristic such as meat yield of lobsters,embodiments of the present invention are also applicable to othercrustaceans, and can be applied to determining a physical characteristicof any product in which perceived quality is at least partially afunction of water content, and more particularly intracellular vs.extracellular water content.

What has been described is merely illustrative of the application of theprinciples of the invention. Other arrangements and methods can beimplemented by those skilled in the art without departing from thepresent invention.

1. A method comprising: determining a minimum peak resonant frequencyF_(resonant) _(—) _(min) and peak resonant amplitude A_(resonant) _(—)_(min) at F_(resonant) _(—) _(min) of an electromagnetic resonantcircuit when loaded by a seafood product; and estimating a physicalcharacteristic of the seafood product based on a slope defined by:(A_(resonant) _(—) _(ref)−A_(resonant) _(—) _(min))/(F_(resonant) _(—)_(ref)−F_(resonant) _(—) _(min)), where F_(resonant) _(—) _(ref) is areference peak resonant frequency of the electromagnetic resonantcircuit in an unloaded state, and A_(resonant) _(—) _(ref) is areference peak resonant amplitude of the electromagnetic resonantcircuit in the unloaded state.
 2. The method according to claim 1,further comprising: determining the reference peak resonant frequencyF_(resonant) _(—) _(ref) and the reference peak resonant amplitudeA_(resonant) _(—) _(ref) of the electromagnetic resonant circuit in theunloaded state.
 3. The method according to claim 1, further comprising:determining a weight of the seafood product, wherein estimating thephysical characteristic comprises estimating the physical characteristicbased on the slope and the weight of the seafood product.
 4. The methodaccording to claim 2, wherein determining F_(resonant) _(—) _(ref) andA_(resonant) _(—) _(ref) comprises: applying a plurality of excitationfrequencies to the electromagnetic resonant circuit in the unloadedstate; measuring an amplitude of an output of the electromagneticresonant circuit for each one of the excitation frequencies; determiningA_(resonant) _(—) _(ref) as a peak amplitude of the measured amplitudes;and determining F_(resonant) _(—) _(ref) as the excitation frequencycorresponding to the peak amplitude of the measured amplitudes.
 5. Themethod according to claim 2, wherein determining F_(resonant) _(—)_(ref) and A_(resonant) _(—) _(ref) comprises: maintaining a record ofpeak resonant amplitudes and frequencies in previous unloaded states;applying a plurality of excitation frequencies to the electromagneticresonant circuit in the current unloaded state; measuring an amplitudeof an output of the electromagnetic resonant circuit for each one of theexcitation frequencies; determining A_(resonant) _(—) _(ref) as arolling average of a number of the peak resonant amplitudes of theprevious unloaded states and the peak amplitude of the current measuredamplitudes; and determining F_(resonant) _(—) _(ref) as a rollingaverage of a number of the peak resonant frequencies of the previousunloaded states and the peak resonant frequency of the current measuredamplitudes corresponding to the peak amplitude of the current measuredamplitudes.
 6. The method according to claim 1, further comprising:maintaining a database of A_(resonant) _(—) _(ref), A_(resonant) _(—)_(min), F_(resonant) _(—) _(ref) and F_(resonant) _(—) _(min) for eachseafood product.
 7. The method according to claim 6, further comprising:maintaining the estimated physical characteristic for each seafoodproduct in the database.
 8. The method according to claim 1, furthercomprising: performing linear regression on the slope to determine alinear relationship between the slope and the physical characteristic.9. The method according to claim 1, further comprising: determining athreshold as a boundary between quality grades; and determining aquality grade of the seafood product by comparing the slope to thethreshold.
 10. The method according to claim 9, wherein determining thethreshold comprises performing a data mining algorithm.
 11. The methodaccording to claim 1, further comprising: calibrating by: determining aslope for a calibration seafood product with a known physicalcharacteristic; and adjusting a function for estimating the physicalcharacteristic based on any discrepancy between the known physicalcharacteristic and the physical characteristic estimate based on thedetermined slope.
 12. The method according to claim 1, wherein theseafood product comprises a plurality of specimens.
 13. The methodaccording to claim 14, wherein the plurality of specimens are containedin a crate.
 14. The method according to claim 1, further comprising:reading an ID from a Radio Frequency Identification (RFID) tagassociated with the seafood product with the electromagnetic resonantcircuit; and associating the ID of the RFID tag associated with theseafood product with information relating to the estimation of thephysical characteristic of the seafood product.
 15. The method accordingto claim 14, wherein associating the ID of the RFID tag associated withthe seafood product with information relating to the estimation of thephysical characteristic of the seafood product comprises at least oneof: transmitting, via the electromagnetic resonant circuit, informationrelating to the estimation of the physical characteristic of the seafoodproduct to the RFID tag associated with the seafood product for storageon the RFID tag; and storing the information relating to the estimationof the physical characteristic of the seafood product in a database,such that the information is associated with the ID of the RFID tag. 16.The method according to claim 15, further comprising: reading the RFIDtag associated with the seafood product to retrieve the informationrelating to the estimation of the physical characteristic of the seafoodproduct associated with the RFID tag; and sorting the seafood productinto one of at least two grades based on the information retrieved fromthe RFID tag.
 17. A system comprising: a sensor comprising anelectromagnetic resonant circuit; a controller, functionally connectedto the electromagnetic resonant circuit, that: determines a minimum peakresonant frequency F_(resonant) _(—) _(min) and peak resonant amplitudeA_(resonant) _(—) _(min) at F_(resonant) _(—) _(min) of theelectromagnetic resonant circuit when the electromagnetic resonantcircuit is loaded by a seafood product; and estimates a physicalcharacteristic of the seafood product based on a slope defined by:(A_(resonant) _(—) _(ref)−A_(resonant) _(—) _(min))/(F_(resonant) _(—)_(ref)−F_(resonant) _(—) _(min)), where F_(resonant) _(—) _(ref) is areference peak resonant frequency of the electromagnetic resonantcircuit in an unloaded state, and A_(resonant) _(—) _(ref) is areference peak resonant amplitude of the electromagnetic resonantcircuit in the unloaded state.
 18. The system according to claim 17,wherein the controller also determines the reference peak resonantfrequency F_(resonant) _(—) _(ref) and the reference peak resonantamplitude A_(resonant) _(—) _(ref) of the electromagnetic resonantcircuit in the unloaded state.
 19. The system according to claim 17,further comprising: a weight scale, functionally connected to thecontroller, that determines a weight of the seafood product, wherein thecontroller estimates the physical characteristic based on the slope andthe weight of the seafood product.
 20. The system according to claim 18,wherein the controller comprises a variable frequency source, andwherein the controller determines F_(resonant) _(—) _(ref) andA_(resonant) _(—) _(ref) by: controlling the variable frequency sourceto apply a plurality of excitation frequencies to the electromagneticresonant circuit in the unloaded state; measuring an amplitude of anoutput of the electromagnetic resonant circuit for each one of theexcitation frequencies; determining A_(resonant) _(—) _(ref) as a peakamplitude of the measured amplitudes; and determining F_(resonant) _(—)_(ref) as the excitation frequency corresponding to the peak amplitudeof the measured amplitudes.
 21. The system according to claim 17,wherein the controller: maintains a record of peak resonant amplitudesand frequencies in previous unloaded states; determines A_(resonant)_(—) _(ref) as a rolling average of a number of the peak resonantamplitudes of the previous unloaded states and the peak amplitude of thecurrent measured amplitudes; and determines F_(resonant) _(—) _(ref) asa rolling average of a number of the peak resonant frequencies of theprevious unloaded states and the peak resonant frequency of the currentmeasured amplitudes corresponding to the peak amplitude of the currentmeasured amplitudes.
 22. The system according to claim 17, furthercomprising: a server having a database in communication with thecontroller, wherein the controller stores a record in the database ofthe estimated physical characteristic, A_(resonant) _(—) _(ref),A_(resonant) _(—) _(min), F_(resonant) _(—) _(ref) and F_(resonant) _(—)_(min) for each seafood product.
 23. The system according to claim 17,wherein the electromagnetic resonant circuit comprises: twosubstantially co-planar plates separated by a gap; an inductor having afirst end and a second end respectively functionally connected to thetwo substantially co-planar plates; a tickler coil inductively coupledto the inductor; and a sense coil inductively coupled to the inductor,wherein the controller applies a plurality of excitation frequencies tothe tickler coil and determines F_(resonant) _(—) _(min) andA_(resonant) _(—) _(min) based on an output of the sense coil when theelectromagnetic resonant circuit is loaded by the seafood product. 24.The system according to claim 17, further comprising: a biologiststation console functionally connected to the controller, the biologiststation console allowing a user to enter a known physical characteristicof a calibration seafood product, wherein the controller: determines aslope for the calibration seafood product with the known physicalcharacteristic; and adjusts a function for estimating the physicalcharacteristic based on any discrepancy between the known physicalcharacteristic and the physical characteristic estimate based on thedetermined slope.
 25. The system according to claim 17, wherein theelectromagnetic resonant circuit comprises three or more substantiallyplanar plates separated by gaps.
 26. The system according to claim 25,wherein the three or more substantially planar plates define a volume.27. The system according to claim 17, wherein the seafood productcomprises a plurality of specimens.
 28. The system according to claim17, wherein the electromagnetic resonant circuit is part of a RadioFrequency Identification (RFID) reader.
 29. The system according toclaim 28, wherein the controller is configured to perform at least oneof the following steps: transmit, via the electromagnetic resonantcircuit, information relating to the estimation of the physicalcharacteristic of the seafood product to an RFID tag associated with theseafood product; and store the information relating to the estimation ofthe physical characteristic of the seafood product in a database, suchthat in the database the information is associated with an ID of theRFID tag associated with the seafood product.
 30. The system accordingto claim 29, further comprising: a second RFID reader comprising asecond electromagnetic resonant circuit configured to read the RFID tagassociated with the seafood product to retrieve the information relatingto the estimation of the physical characteristic of the seafood product;and a grader, functionally connected to the RFID reader, configured tosort the seafood product into one of at least two grades based on theinformation retrieved from the RFID tag.
 31. The system according toclaim 30, wherein the information relating to the estimation of thephysical characteristic of the seafood product comprises a grade of theseafood product, and wherein sorting the seafood product comprisessorting the seafood product based on the grade of the seafood productstored on the RFID tag.
 32. A method comprising: driving a first probeof a plurality of probes with a test signal, when the plurality ofprobes is loaded by a seafood product; measuring received test signalsat one or more other probes of the plurality of probes; and estimating aphysical characteristic of the seafood product based on the receivedtest signals.
 33. The method according to claim 32, wherein drivingcomprises sequentially driving each of the probes of the plurality ofprobes with the test signal.
 34. The method according to claim 32,wherein measuring comprises measuring the received signals with each ofthe other probes of the plurality of probes.
 35. The method according toclaim 32, further comprising: determining calibration references by:driving the first probe of the plurality of probes with a test signal,when the plurality of probes is unloaded; and measuring received testsignals at the one or more other probes of the plurality of probes,wherein estimating comprises estimating based on the calibrationreferences and the test signals received when the plurality of probes isloaded by the seafood product.
 36. The method according to claim 35,wherein estimating comprises estimating the physical characteristic as afunction of a difference in magnitude between the received test signalsand the calibration references.
 37. The method according to claim 32,wherein driving comprises driving the first probe with a plurality oftest signals, each test signal corresponding to one of a plurality offrequencies.
 38. The method according to claim 32, wherein the seafoodproduct comprises a plurality of specimens, and wherein estimating aphysical characteristic of the seafood product comprises estimating anaverage physical characteristic of the plurality of specimens.
 39. Themethod according to claim 32 further comprising sorting the seafoodproduct into one of at least two grades based on the estimated physicalcharacteristic.
 40. The method according to claim 32 further comprisingcontacting the plurality of probes to the seafood product.
 41. Themethod according to claim 40, wherein the seafood product comprises alobster, and contacting the plurality of probes to the seafood productcomprises contacting the plurality of probes to an underside of a tailof the lobster.
 42. The method according to claim 41, wherein measuringreceived test signals at one or more other probes of the plurality ofprobes comprises: measuring relative impedance of tissue occupying spacebetween the first probe and the one or more other probes of theplurality of probes; and generating a profile of tissue impedance alongthe plurality of probes, wherein estimating a physical characteristic ofthe seafood product based on the received test signals comprisesestimating the physical characteristic based on a gradient of theprofile.
 43. A system comprising: a sensor comprising a plurality ofprobes; a controller, functionally connected to the sensor, that: drivesa first probe of the plurality of probes with a test signal, when theplurality of probes is loaded by a seafood product; measures receivedtest signals at one or more other probes of the plurality of probes; andestimates a physical characteristic of the seafood product based on thereceived test signals.
 44. The system according to claim 43, wherein theplurality of probes comprises a plurality of plates defining a volume,and wherein the controller drives a first plate of the plurality ofplates with the test signal when the plurality of plates is loaded bythe seafood product within the volume.
 45. The system according to claim44, wherein the seafood product comprises a plurality of specimens. 46.The system according to claim 45, wherein the plurality of specimens arecontained in a crate.
 47. The system according to claim 43, wherein thecontroller determines calibration references by: driving the first probeof the plurality of probes with a test signal, when the plurality ofprobes is unloaded; and measuring received test signals at the one ormore other probes of the plurality of probes, wherein estimatingcomprises estimating based on the calibration references and the testsignals received when the plurality of probes is loaded by the seafoodproduct.
 48. The system according to claim 43, wherein the controllerdrives each of the plurality of probes with the test signalindividually, and while each probe is driven, measures the received testsignals at the one or more other test probes.
 49. The system accordingto claim 43, wherein the controller comprises a variable frequencysource that generates the test signal, and wherein the test signalcomprises a plurality of test signals, each test signal having one of aplurality of frequencies.
 50. The system according to claim 44, whereinthe plates are u-shaped, and the volume comprises a convex-shaped volumegenerally defined by the u-shaped plates.
 51. The system according toclaim 50, wherein the plurality of plates comprises four u-shapedplates.
 52. The system according to claim 44, further comprising anelectromagnetic shield surrounding an outer periphery of the pluralityof plates that substantially confines electromagnetic fields generatedby the plurality of plates to the volume defined by the plurality ofplates.
 53. The system according to claim 52, wherein the plurality ofplates are mounted on non-conducting standoffs that provide galvanicisolation between the shield and the plurality of plates.
 54. The systemaccording to claim 43, wherein the seafood product comprises a lobster,and wherein the plurality of probes are arranged for contact on anunderside of a tail of the lobster.
 55. The system according to claim54, wherein the controller: measures relative impedance of tissueoccupying space between the first probe and the one or more other probesof the plurality of probes; generates a profile of tissue impedancealong the plurality of probes; and estimates the physical characteristicof the seafood product based on a gradient of the profile.
 56. Ahandheld device for estimating a physical characteristic of a seafoodproduct comprising the system according to claim
 42. 57. A methodcomprising: reading an ID from a Radio Frequency Identification (RFID)tag associated with a seafood product with an electromagnetic resonantcircuit; determining a loading effect of the seafood product on theelectromagnetic resonant circuit when loaded by the seafood product;estimating a physical characteristic of the seafood product based on theloading effect of the seafood product; and associating the ID from theRFID tag associated with the seafood product with information relatingto the estimation of the physical characteristic of the seafood product.58. The method according to claim 57, wherein associating the ID fromthe RFID tag associated with the seafood product with informationrelating to the estimation of the physical characteristic of the seafoodproduct comprises at least one of: transmitting, via the electromagneticresonant circuit, the information relating to the estimation of thephysical characteristic of the seafood product to the RFID tagassociated with the seafood product for storage on the RFID tag; andstoring the information relating to the estimation of the physicalcharacteristic of the seafood product in a database, such that theinformation is associated in the database with the ID of the RFID tag.59. The method according to claim 57, wherein the electromagneticresonant circuit comprises an antenna, and wherein determining theloading effect of the seafood product on the electromagnetic resonantcircuit comprises at least one of: determining a change in impedance ofthe antenna between an unloaded state and when loaded by the seafoodproduct; determining a phase angle of a standing wave ratio (SWR) of theantenna; and determining a change in the gain of the antenna between theunloaded state and when loaded by the seafood product.
 60. The methodaccording to claim 58, further comprising: reading the RFID tag toretrieve the information relating to the estimation of the physicalcharacteristic of the seafood product from the RFID tag associated withthe seafood product; and sorting the seafood product into one of atleast two grades based on the information retrieved from the RFID tag.61. The method according to claim 60, wherein the information relatingto the estimation of the physical characteristic of the seafood productcomprises a grade of the seafood product; and sorting the seafoodproduct comprises sorting the seafood product based on the grade of theseafood product stored on the RFID tag.
 62. The method according toclaim 57, wherein operating frequency of the electromagnetic resonantcircuit is in a range of about 1 MHz to about 100 MHz.
 63. The methodaccording to claim 57, further comprising: determining a weight of theseafood product, wherein estimating the physical characteristiccomprises estimating the physical characteristic based on the loadingeffect and the weight of the seafood product.
 64. The method accordingto claim 58, further comprising: maintaining the database such that foreach seafood product the database maintains a record of the ID of theRFID tag associated with the seafood product and at least one of: theloading effect of the seafood product and the estimated physicalcharacteristic of the seafood product.
 65. The method according to claim57, further comprising: performing linear regression on the loadingeffect to determine a linear relationship between the loading effect andthe physical characteristic.
 66. The method according to claim 57,further comprising: determining a threshold as a boundary betweenquality grades; and determining a quality grade of the seafood productby comparing the loading effect to the threshold.
 67. The methodaccording to claim 66, wherein determining the threshold comprisesperforming a data mining algorithm.
 68. The method according to claim57, further comprising: calibrating by: determining a loading effect onthe electromagnetic resonant circuit for a calibration seafood productwith a known physical characteristic; and adjusting a function forestimating the physical characteristic based on any discrepancy betweenthe known physical characteristic and the physical characteristicestimate based on the determined loading effect for the calibrationseafood product.
 69. The method according to claim 57, wherein theseafood product comprises a plurality of specimens.
 70. A systemcomprising: an electromagnetic resonant circuit; a controller,functionally connected to the electromagnetic resonant circuit, that:reads an ID from a Radio Frequency Identification (RFID) tag associatedwith a seafood product with the electromagnetic resonant circuit;determines a loading effect of the seafood product on theelectromagnetic resonant circuit when the electromagnetic resonantcircuit is loaded by the seafood product; estimates a physicalcharacteristic of the seafood product based on the determined loadingeffect of the seafood product; and associates the ID from the RFID tagassociated with the seafood product with information relating to theestimation of the physical characteristic of the seafood product. 71.The system according to claim 70, wherein the controller associates theID from the RFID tag associated with the seafood product withinformation relating to the estimation of the physical characteristic ofthe seafood product by performing at least one of the following steps:transmitting, via the electromagnetic resonant circuit, the informationrelating to the estimation of the physical characteristic of the seafoodproduct to the RFID tag associated with the seafood product; and storingthe information relating to the estimation of the physicalcharacteristic of the seafood product in a database, such that theinformation is associated in the database with the ID of the RFID tag.72. The system according to claim 70, wherein the electromagneticresonant circuit comprises an antenna, and wherein the controllerdetermines the loading effect of the seafood product on theelectromagnetic resonant circuit by determining at least one of: achange in impedance of the antenna between an unloaded state and whenloaded by the seafood product; a phase angle of a standing wave ratio(SWR) of the antenna; and a change in the gain of the antenna betweenthe unloaded state and when loaded by the seafood product.
 73. Thesystem according to claim 71, further comprising: an RFID readercomprising a second electromagnetic resonant circuit configured to readthe RFID tag associated with the seafood product to retrieve theinformation relating to the estimation of the physical characteristic ofthe seafood product; and a grader, functionally connected to the RFIDreader, configured to sort the seafood product into one of at least twogrades based on the information retrieved from the RFID tag.
 74. Thesystem according to claim 73, wherein the information relating to theestimation of the physical characteristic of the seafood productcomprises a grade of the seafood product; and sorting the seafoodproduct comprises sorting the seafood product based on the grade of theseafood product stored on the RFID tag.
 75. The system according toclaim 70, wherein operating frequency of the electromagnetic resonantcircuit is in a range of about 1 kHz to about 100 MHz.
 76. The systemaccording to claim 70, further comprising: a weight scale, functionallyconnected to the controller, configured to determine a weight of theseafood product, wherein the controller estimates the physicalcharacteristic by estimating the physical characteristic based on theloading effect and the weight of the seafood product.
 77. The systemaccording to claim 71, further comprising: the database in communicationwith the controller that for each seafood product maintains a record ofthe ID of the RFID tag relating to the seafood product and at least oneof: the loading effect of the seafood product and the estimated physicalcharacteristic of the seafood product.
 78. The system according to claim70, wherein the controller performs linear regression on the loadingeffect to determine a linear relationship between the loading effect andthe physical characteristic.
 79. The system according to claim 70,wherein the controller: determines a threshold as a boundary betweenquality grades; and determines a quality grade of the seafood product bycomparing the loading effect to the threshold.
 80. The system accordingto claim 77, wherein the controller performs a data mining algorithm todetermine the threshold.
 81. The system according to claim 70, whereinthe controller comprises a variable frequency source.
 82. The systemaccording to claim 70, further comprising: a biologist station consolefunctionally connected to the controller, the biologist station consoleallowing a user to enter a known physical characteristic of acalibration seafood product, wherein the controller: determines theloading effect of the calibration seafood product with the knownphysical characteristic on the electromagnetic resonant circuit; andadjusts a function for estimating the physical characteristic based onany discrepancy between the known physical characteristic and thephysical characteristic estimate based on the determined loading effectof the calibration seafood product.
 83. The system according to claim70, wherein the seafood product comprises a plurality of specimens.